We were getting pyflakes lint error output without line numbers like
this:
pyflakes | if user_profile.is_realm_admin and
pyflakes | ^
pyflakes |
Apparently the cause was that stdout and stderr was getting mixed
badly, creating "unused import"s lines that had the first of that
error (containing the line number) just above.
As a result, printing out the lines of output from pyflakes' merged
stdout/stderr feed looked like this:
b"zproject/settings.py:95: 'from .prod_settings import *' used; unable to detect undefined nameszerver/views/users.py:49:39: invalid syntax\n"
Note the lack of newline in between the end of the first error at
"names" and the start of the second at "zerver".
This appears to be a change in Pyflakes behavior when we switched to
Python 3; probably they're missing a flush() somewhere.